Green River, Wyoming in the context of "Interstate 80 in Wyoming"

The Powell Geographic Expedition of 1869, led by American naturalist John Wesley Powell, was the first thorough cartographic and scientific investigation of long segments of the Green and Colorado rivers in the southwestern United States, including the first recorded passage of white men through the entirety of the Grand Canyon. The expedition, which lasted approximately three months during the summer of 1869, embarked from Green River Station, Wyoming Territory and traveled downstream through parts of the present-day states of Colorado and Utah before reaching the confluence of the Colorado and Virgin rivers in present-day Arizona and Nevada . Despite a series of hardships, including losses of boats and supplies, near-drownings, and the eventual departures of several crew members, the voyage produced the first detailed descriptions of much of the previously unexplored canyon country of the Colorado Plateau.

Powell retraced part of the 1869 route on a second expedition in the winter of 1871–72. In 1875, he published a classic account of the first expedition (interspersed with elements from the second) called Report on the Exploration of the Colorado River of the West and Its Tributaries, which was revised and reissued in 1895 as The Exploration of the Colorado River and Its Canyons.